The object of this research is to promote understanding of the abnormal hemoglobins--their identification, incidence, structure, pathogenetic mechanisms, and clinical manifestations. Blood samples are obtained from patients with hemoglobinopathies, from here and from other institutions for whom we serve as a reference laboratory. When indications arise, structural studies of the hemoglobin are obtained, as well as clinical, hematologic and genetic data. Intraerythrocytic precipitations are studied microscopically and analyzed for hemoglobin and globin. Methods of study include various kinds of electrophoresis, chromatography, microscopy and chemical analysis, as well as the standard hematologic and clinical techniques. We can now identify, with a high degree of accuracy, several dozen hemoglobin variants of the basis of their properties (and those of their globin-chains) in several electrophoretic systems. Other hemoglobin variants, as many as possible, will be added to this number.